Increased oxidative stress in patients with chronic obstructive pulmonary disease (COPD) as measured by redox status of plasma coenzyme Q10

STUDY OBJECTIVES: The percentage of oxidized coenzyme Q10 in total coenzyme Q10 (%CoQ-10) has been shown to indicate the degree of systemic oxidative stress. Chronic obstructive pulmonary disease (COPD) is regarded as a systemic disease that is linked to oxidative stress in its pathogenesis. In this study, the plasma %CoQ-10 levels in COPD patients were determined and assessed. In addition, the effect of oxygen supplementation on plasma %CoQ-10 was also evaluated. MATERIAL AND METHODS: Thirteen COPD patients who had not received oxygen supplementation (COPD-Pt), five COPD patients who had received oxygen supplementation (COPD + O2) and 20 age-matched control subjects (CONTROL) were enrolled. We have also enrolled 83 young healthy non/slight smokers (smoking index <20 pack-year) and 24 young healthy smokers (smoking index > or = 20 pack-year) in order to assess the effect of smoking history on %CoQ-10 level. Their plasma was collected and plasma %CoQ-10 levels were determined and compared. RESULTS AND CONCLUSION: The plasma %CoQ-10 of COPD-Pt was 6.3 +/- 2.3, significantly higher than that of CONTROL, 4.7 +/- 1.6 (p < 0.05), indicating an increased oxidative stress in the patients. In contrast, no significant difference in %CoQ-10 was observed between young healthy non/slight smokers (%CoQ-10 = 3.2 +/- 0.9) and young healthy smokers (%CoQ-10 = 3.7 +/- 1.3). Our observation of five COPD patients who received an oxygen supplementation revealed that their %CoQ-10 values (4.0 +/- 1.5) were significantly lower than those in COPD-Pt subjects (p < 0.05), suggesting that oxygen supplementation ameliorates the oxidative stress. In contrast, our study showed that no significant difference was observed among the three groups in plasma levels of Vitamin C or E. In conclusion, plasma %CoQ-10 levels are increased in COPD patients and oxygen supplementation attenuates this increasing effect by COPD. This implies that %CoQ-10 might be used practically to assess the COPD patients systemically.